With the expansion of tennis as a participant sport, the construction of tennis courts has multiplied. Tennis courts have been constructed of many types of surfaces including grass, clay, dirt, asphalt or macadam, concrete, wood, linoleum, brick and synthetic turf. Wood and linoleum are used primarily for indoor courts. Outdoor courts are generally surfaced with concrete, asphalt or a synthetic surface.
Concrete and asphalt require very little maintenance but their initial construction costs are high. Also, the hard unyielding surfaces of the concrete and asphalt cause excessive strain on the legs and feet of players.
Clay courts are less expensive to construct than concrete or asphalt, but a clay court requires a great deal of maintenance. Clay courts are generally referred to as providing "true bounce" and also have been recognized as being the most comfortable with regard to strain on the legs and feet.
Elastomeric compositions which are applied over a concrete or asphalt surface are commonly used in the new construction of tennis courts. Also, synthetic turf tennis courts have been provided. See, for example, U.S. Pat. No. 4,044,179 wherein a construction is disclosed which apparently duplicates that of a grass court. Basically, in this reference, a pile fabric is disposed on a relatively flexible sub-surface. A compacted layer of granular material is disposed among the pile of the fabric.
U.S. Pat. No. 3,438,312 discloses an aperatured synthetic tennis court surface.
It has been recognized that aggregate, mixed either alone or with a bituminous material and/or a polymeric material, is suitable for tennis courts, see U.S. Pat. No. 3,012,485. It is known when some road surfaces are laid that aggregate is subsequently added to create a non-skid surface, see U.S. Pat. Nos. 2,925,831 and 3,901,615.
In spite of all these various constructions of surfaces, a tennis court surface has not yet been developed which will be both maintenance-free and duplicate the properties of a conventional clay court. That is, a court which will provide a sliding granular surface of the proper resiliency.
The present invention relates to a tennis court composition and a method of constructing the same. The composition is applied to a substrate which substrate does not form a part of the invention. The composition comprises at least two laminae, a first adhesive lamina contacting the substrate and a second lamina of free-flowing aggregate coextensive with the surface of the first lamina and of a defined thickness.
The first lamina is a bonding adhesive composition, such as a resinous film-forming vehicle capable of ambient temperature hardening, preferably an elastomeric polymer. Further either alone or in combination therewith, a hydrocarbonaceous binder may be used. Such a binder may employ a bituminous material such as a bituminous liquid composed of a mixture of hydrogen, carbon and oxygen conforming to the specifications defined by the American Association of the State Highway and Transportation Officials. The bituminous liquid includes asphalt emulsions at an application temperature of between 50.degree. F. to 150.degree. F., or a combination of mineral oils and cut-back asphalts at application temperatures of between 100.degree. F. to 200.degree. F. Also, a paving grade asphalt may be used which would include substances containing bitumens or pyrobitumens, pyrogeneous distillates and tar, pyrogeneous waxes and pyrogeneous residues (pitches and asphalts).
The film-forming vehicle may be any elastomeric polymer. Elastomeric is defined as having the ability of a polymer strip to return to its approximate initial length after elongation to below its breaking or fracture point.
Within the scope of the invention, solvent systems may be used containing either moisture or catalyst-cured urethanes; polyesters which are esters of saturated alcohols and unsaturated acids; polyamide resins such as the VERSAMIDS and vegetable oil modified polyamids as well as epoxy resins. Aqueous emulsion vehicles are preferably employed, for example, vinyl-resin, polyvinyl acetate, acrylics and acrylic ester copolymer emulsions, synthetic and natural latex and the like. Some resins such as the polyesters, the acrylates, methacrylates, and particularly acrylate-acid polymers and copolymers can be used in either solvent or emulsion systems.
The particles of aggregate admixed with the first lamina are of a particle size and amount such that when the first lamina is spread to its final thickness, between 30 to 70%, preferably 50% of the upper surface of the composition will be coated aggregate extending beyond the upper level of the applied film-forming vehicle. This irregular non-uniform upper surface structurally forms a dimensionally stable non-bonding upper adhesive surface.
The second lamina is a free-flowing aggregate of defined thickness and particle size. The second lamina is relatively held in place by the adhesive upper surface of the first lamina and this results in a sliding friction between the first and second laminae. The thickness of the second lamina is such that in combination with the first lamina, the "true bounce" of a tennis ball is achieved.
My invention in a preferred embodiment is a tennis court composition which comprises a first lamina of an elastomeric film-forming vehicle having admixed therewith particles of aggregate comprising 25 to 75% of the total lamina by volume. The composition is applied to a substrate the lower surface adhering to the substrate, the upper surface characterized by a roughened non-uniform gravel-like surface. A second lamina of free-flowing aggregate contacts the upper surface of the first lamina, the second lamina forming with the first lamina a resilient composition, the second lamina engaged to the first by the gravel-like surface in a sliding friction relationship. The thickness of the second lamina is one to three times the total thickness of the first lamina.